The government is keeping its options open to keep the Millennium Dome as an entertainment attraction, in case the Legacy consortium fails in its bid to turn the £1b tent into "Knowledge City".

But last night ministers closed ranks with Legacy -the "preferred bidder" in the sale of the dome - and rejected pleas to reopen the bidding by Tory and Liberal Democrat MPs and other opponents of the Legacy plan.

"If Legacy fails we will still have an option to turn it into a visitor attraction," said one minister as the dome's media critics claimed incorrectly that crucial infrastructure such as escalators was being removed from the dome. In fact only rented equipment such as lighting and gantries is being removed, to save money.

None of the dome's £50m contents will be sold before February 27, and then only if Legacy's negotiations with English Partnership, the responsible government agency, succeed. The deadline for these talks is February 15.

Last night Legacy, a consortium headed by the property developer Robert Bourne, with the heavy backing of Dublin-based Treasury Holdings, reaffirmed its commitment to its bid and predicted "a satisfactory conclusion".

Ministers are determined not to be caught out again after the dome's huge cost overruns, and have inserted a clawback clause into Legacy's contract to ensure a share of any windfall profits from projects such as luxury housing.

Ken Livingstone, London's mayor, also weighed in yesterday by saying that so much public money had been swallowed by the dome that up to 50% of any homes built on the Greenwich site must be affordable by ordinary buyers.

The pro-dome campaigner Simon Jenkins urged ministers to avoid a premature "fire sale" at Greenwich merely because Labour wanted to be free of a major embarrassment ahead of the coming election.

Mr Jenkins and the Tory culture and transport spokesmen, Peter Ainsworth and Bernard Jenkin, want P Y Gerbeau, the dome's exhuberant chief executive, to be allowed "at least a year to see what he can do" to keep the dome alive now that it is belatedly being seen as a success.

"John Prescott has a clear duty to reopen the bidding now. There are many organisations showing an interest in bidding, but Mr Prescott is locking them out for political reasons," Mr Jenkin complained.

Though some ministers doubt that Legacy has the experience to pull off its ambitious vision, they insist that it emerged from an open competition after the Nomura consortium's bid foundered last November. To allow late-comers to join the bidding now would be wrong, they say.

Legacy wants to use the dome's vast space to house lightweight and flexible office and exhibition facilities that will attract professional services, IT firms and even academic research bodies. Up to 9,000 people could work there, said Legacy's public relations agency, Bell Pottinger.